Sample collection, quantification, and identification in preparative anticircular planar chromatography

Abstract

AbstractA preparative anticircular chromatography (PACH) device was constructed to elucidate different applications of separation problems as well as to compare different sample collection techniques in this particular PLC mode. An anticircular PC apparatus had to be established which allowed the utilization of 20 X 20 cm thin‐layer plates as well as sampling positioning at any given radius. Typical solvent migration times were 8–12 minutes and ca. 8–10 ml of solvent was needed for an entire 20 cm plate. It was shown that peak broadening effects due to diffusion during long migration could be avoided in the same way as for analytical anticircular PLC on 10 X 10 plates. On the other hand, longer migration distances allow increased resolution, in turn allowing higher sample loads, particularly in the case of trace compound enrichment. A full description of the apparatus is given, including the sampling device.Different sample collection techniques were tried and evaluated, including the through‐flow technique by on‐line center collection for plate washing as well as classical scraping‐off of interesting zones. Further evaluation of the method included quantification and evaluation of consistency by UV/VIS scanning after spot‐visualization. Several application examples are given to illustrate the efficiency of the preparative anticircular PLC‐system.